Abstract: Objectives: The preparation of antioxidant enzymatic hydrolysate (AEH) from Sepia esculenta by papain hydrolysis and the debittering of AEH by activated carbon adsorption were explored. Meanwhile, the nutritional value of AEH was also evaluated. Methods: The hydrolysis of Sepia esculenta and the debittering of AEH were optimized by orthogonal array design based on hydroxyl free radical scavenging rate and bitterness sensory score, respectively. The amino acid composition of AEH was determined by means of automatic amino acid analyzer. The nutrition value of AEH was analyzed based on its amino acid and chemical scores, calculated using egg protein as standard protein and the WHO/FAO reference model for essential amino acids as an appraisal criterion (EAA). Results: The optimal enzymatic hydrolysis conditions were hydrolysis temperature of 55 ℃, pH 7.0, enzymatic hydrolysis time of 5 h and enzyme amount of 1.0%; the optimal debittering conditions were activated carbon amount of 3.0%, debittering time of 120 min and debittering temperature of 40 ℃. The AEH obtained under these conditions with basically no bitterness had even higher hydroxyl free radical scavenging activity than crude protein extract from Sepia esculenta. The crude protein content of AEH was 18.07%. Meanwhile, AEH was rich in all kinds of amino acids with a total content of 95.95%. Moreover, essential amino acids (EAA) accounted for 42.00% of the total amino acids. The first limited amino acid was Val. The EAA index was 93.7 when compared with egg. The content of palatable and sweet taste amino acids like glutamic acid accounted for 38.68% of the total amino acids. Conclusion: The AEH has strong antioxidant capacity and high nutrition value and can therefore provide an ideal source of protein supplements.

Key words: Sepia esculenta, antioxidant enzymatic hydrolysate (AEH), papain, debittering